1. Field of the Invention
The present invention relates generally to agricultural equipment. More particularly, the present invention relates to a crop raking device that maintains a more consistent position with respect to the ground.
2. Related Art
In typical hay and forage operations, harvest practices become the determining factor as to whether a valuable crop standing in the field will still be valuable when it is in the barn, in the stack, in the silage bag, pit or silo, or in the manger where it is used as feed. Each component of the harvest procedure presents challenges, and each, if handled improperly, poses the risk of seriously devaluing the end product on which the producer depends.
In silage operations various forages are cut green into windrows. Two or more windrows are raked together to create a larger windrow which will satisfy the appetite of modern high capacity forage harvesters. In nearly all dry hay and forage operations, the crop is cut green and then allowed to dry for a period of time. When sufficient drying has occurred, the hay or forage is then inverted for further drying or two or more windrows or swaths of crop are gathered into one larger windrow for further drying and/or to accommodate the next harvest operation of baling, dry chopping, cubing or palletizing.
While great progress has been made in the technologies contributing to hay and forage harvesting, there are still areas that need improvement. In very recent years, raking has become a much more critical component of hay and forage harvesting because the more lucrative markets are demanding cleaner product. Rocks, dirt clods, soil particles, and other debris and contaminants in hay and forage products significantly reduce sales or seriously reduce the price producers can obtain for their product. These contaminants can be introduced into forages during various operations of the harvest. However raking is where most forage contamination occurs. When rake teeth or other portions of a raking device dig into the soil, rather than staying above it, they introduce these contaminants into the forage.
One forage raking system that is relatively effective in minimizing contamination of forage is the basket rake. Basket rakes generally place one or more ground-contacting wheels relatively close to the raking area of the machine, which usually maintains a reasonable operating clearance above the ground. The system is probably the most effective in maintaining a consistent operating height or depth. However, basket rakes are generally considered to be too slow in the commercial hay industry. Consequently, the rake market has moved heavily toward the much faster, but dirtier, wheel rake.
The current design of wheel rakes requires a delicate balance between trying to effectively gather cut hay swaths or windrows (without leaving valuable crop in the field), while trying to keep the rake teeth out of the soil. It is difficult to maintain optimum raking accuracy because large modern wheel rakes cover swaths as wide as 40 feet or more, with operating lengths up to 30 feet. At any given time, within the length and breadth of such an operating area, there can be large enough variations in the field elevation to cause either undesirable contact between the rake teeth and the soil surface, or excessive rake tooth operating height in other locations.
There have not been many significant technological advancements in hay and forage raking for many years. Indeed, until recently, market forces have not particularly focused on the problem of contaminated forage, and players in the market have not complained too loudly about this problem. However, this appears to be changing due to a variety of market forces. Export markets are becoming particularly sensitive to contamination of forages with soil or other soil-borne products because of the perceived risk of biological contamination of their native soils with soil-borne organisms from other countries. Additionally, equipment maintenance is also affected by poor raking performance. Rake teeth are very expensive, and wear out quickly when they frequently contact a soil surface. Furthermore, machinery used in other operations, such as machinery for subsequent harvest operations, bearings, cutting knives, pellet and hay cube dies etc., also wears at an accelerated rate when abrasive soil or aggregate substances are present in the forages they process.
Some attempts have been made within recent years to resolve these problems. Currently the most common method of controlling the operating height or depth of wheel rakes includes the use of flotation springs. These are designed to lighten each individual rake wheel so that when the rake teeth mounted on the outside circumference of the rake wheel contact the soil surface during operation, they do not dig heavily into the soil but will scuff the soil only an inch or two deep upon contact. Unfortunately, this scuffing action is sufficient to dislodge small rocks, gravel, small soil clods, soil particles and other debris, and to propel a portion of these into the forage being raked.
Additionally, if an operator does not adjust the wheel rake regularly, the contact between the rake teeth and the soil can become excessive causing excessive wear and/or breakage of the rake teeth and excessive contamination of the forage being raked. Thousands of tons of forage can be contaminated relatively quickly with poor rake performance.
Another recent attempt to improve wheel rake performance has been to install depth bands on wheel rake systems. These bands are connected to the outer circumference of the rake wheels between each pair of rake teeth in either a loop shape or a “J” shape. If adjusted properly, depth bands provide a depth stop which allows the rake teeth to operate very close to the soil surface without letting the teeth actually penetrate the soil. Rake wheels equipped with these depth bands are also typically suspended with flotation springs to lighten the contact of the depth bands with the soil surface.
Depth bands can work reasonably well in certain soil conditions. However, significant contamination problems still exist in soft soils and sandy soil because the depth bands themselves, being relatively narrow (e.g. about 1 inch wide) can fairly easily penetrate these soil types, allowing both the depth band and the rake teeth to throw soil particles into the forage being raked. There have been reports by owners of these rake systems that the depth bands and the rake teeth both readily move gravel and small rocks into forage.